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