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