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