One vertex per element, one color per generator, with an edge from x to x·s.
(2,6)(7,8)(9,10,13,16)(11,14,19,23)(12,15,20,24)(17,21,18,22)(25,26,30,33)(27,34,29,31)(28,36,38,32)(35,39,37,40)(1,2)(3,7)(4,8)(5,6)(9,11)(10,14)(12,18)(13,19)(15,22)(16,23)(17,20)(21,24)(25,26)(27,34)(28,32)(29,31)(30,33)(35,40)(36,38)(37,39) involution — undirected(1,3,5,4)(2,7,6,8)(9,12)(10,15)(11,17)(13,20)(14,21)(16,24)(18,19)(22,23)(25,27,30,29)(26,31,33,34)(28,37,38,35)(32,40,36,39)(9,10)(11,14)(12,15)(13,16)(17,21)(18,22)(19,23)(20,24)(25,28,30,38)(26,32,33,36)(27,35,29,37)(31,39,34,40)(1,3,5,4)(2,7,6,8)(9,12)(10,15)(11,18)(13,20)(14,22)(16,24)(17,19)(21,23)(25,26)(27,31)(28,32)(29,34)(30,33)(35,39)(36,38)(37,40)(1,4,5,3)(2,8,6,7)(9,11)(10,14)(12,17)(13,19)(15,21)(16,23)(18,20)(22,24)(25,29,30,27)(26,31,33,34)(28,37,38,35)(32,39,36,40)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.