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