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