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