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)(11,16)(12,26)(13,18)(14,19)(15,21)(17,29)(20,31)(22,37)(23,34)(24,35)(25,36)(27,40)(28,39)(30,38)(32,33) involution — undirected(1,3)(2,5)(4,8)(6,7)(9,11,15,25)(10,16,21,36)(12,27,30,32)(13,23,31,24)(14,29,22,28)(17,37,39,19)(18,34,20,35)(26,40,38,33)(9,12)(10,17)(11,22)(13,28)(14,25)(15,30)(16,33)(18,26)(19,35)(20,38)(21,39)(23,27)(24,32)(29,31)(34,37)(36,40) involution — undirected(2,6)(5,7)(9,13,15,31)(10,18,21,20)(11,23,25,24)(12,28,30,29)(14,32,22,27)(16,34,36,35)(17,26,39,38)(19,33,37,40)(3,8)(5,7)(9,14,15,22)(10,19,21,37)(11,12,25,30)(13,27,31,32)(16,26,36,38)(17,35,39,34)(18,40,20,33)(23,29,24,28)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.