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