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