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)(11,13,18,16)(14,17,23,20)(19,21,24,22)(25,26)(27,36)(28,29)(30,35)(31,33)(32,38)(34,39)(37,40)(1,2)(3,6)(4,7)(5,8)(9,11,15,18)(10,16,12,13)(14,19,23,24)(17,22,20,21)(25,27,31,38)(26,32,33,36)(28,35,34,40)(29,37,39,30)(1,3,5,4)(2,6,8,7)(10,12)(11,18)(17,20)(19,24)(26,33)(28,34)(32,36)(35,40)(9,12,15,10)(11,13,18,16)(14,20,23,17)(19,21,24,22)(25,28,31,34)(26,29,33,39)(27,35,38,40)(30,32,37,36)(9,13)(10,11)(12,18)(14,22)(15,16)(17,24)(19,20)(21,23)(25,29)(26,34)(27,37)(28,33)(30,38)(31,39)(32,40)(35,36) involution — undirected(1,4,5,3)(2,7,8,6)(9,14,15,23)(10,17,12,20)(11,19,18,24)(13,21,16,22)(25,30,31,37)(26,35,33,40)(27,29,38,39)(28,32,34,36)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.