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