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