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