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