One vertex per element, one color per generator, with an edge from x to x·s.
(2,6)(7,8)(9,10,14,18)(11,15,21,24)(12,16,20,23)(13,17,19,22)(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)(10,15)(12,19)(13,20)(14,21)(16,22)(17,23)(18,24)(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)(10,16)(11,13)(14,20)(15,17)(18,23)(19,21)(22,24)(25,27,30,29)(26,31,33,34)(28,37,38,35)(32,40,36,39)(9,10)(11,15)(12,16)(13,17)(14,18)(19,22)(20,23)(21,24)(25,28,30,38)(26,32,33,36)(27,35,29,37)(31,39,34,40)(1,4,5,3)(2,8,6,7)(9,12)(10,16)(11,19)(13,21)(14,20)(15,22)(17,24)(18,23)(25,26)(27,31)(28,32)(29,34)(30,33)(35,39)(36,38)(37,40)(9,13,14,19)(10,17,18,22)(11,20,21,12)(15,23,24,16)(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.