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