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