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