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